setup greenkeeper, remove unused dep

[skip ci]

package-lock.json

@@ -10913,14 +10913,6 @@
         }
       }
     },
-    "workerize-loader": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/workerize-loader/-/workerize-loader-1.0.1.tgz",
-      "integrity": "sha512-OwkHyCnSrxnVXDJhyYlM2wcYW9RfE/DH76EmWLYJDcfWyiw53tyrs+WAUEBzRmiaf6f2W1ZNQ/Lky+PRcqDwew==",
-      "requires": {
-        "loader-utils": "1.1.0"
-      }
-    },
     "wrap-ansi": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-2.1.0.tgz",

package.json

@@ -77,7 +77,6 @@
     "web-animations-js": "^2.3.1",
     "webpack": "^4.5.0",
     "webpack-bundle-analyzer": "^2.11.1",
-    "workerize-loader": "^1.0.1",
     "yargs": "^10.1.1"
   },
   "devDependencies": {
@@ -144,5 +143,10 @@
       "webpack.client.config.js",
       "webpack.server.config.js"
     ]
+  },
+  "greenkeeper": {
+    "ignore": [
+      "sapper"
+    ]
   }
 }